Antenna



14, 1949., w SICHAK 2,473,454

ANTENNA Filed Jflly 9, 1945 INVENTOR WILLIAM SICHAK ATTORN EY Patented June 14, 1949 ANTENNA William Sichak, Cambridge, Mass, assignor, by mesne assignments, to the United. States of America as represented by the Secretary of War Application July 9, 1945, Serial No. 604,028

4 Claims.

This invention relates to antennae and more particularly to antennae suitable for use in high frequency communication systems.

Among the objects of this invention are: to provide compactness of structure using a paraboloidal reflector; to provide a desired polarization; and to enable rotation of the antenna.

Further objects and advantages of this invention will be apparent from the description herein.

The drawing shows a preferred embodiment of the invention.

Referring now to the drawing, 5 is a paraboloid reflector having a metallic concave surface suitable for reflecting high frequency electromagnetic energy. Waveguide 6 extends through the paraboloid near its vertex along its axis, on the focal line of the paraboloid. Bends such as l, 8 and 9 are afforded in the waveguide 6 so that the aperture of this waveguide terminates at or near the focal point of the parabolic surface and directs energy against the reflector.

It is apparent that the illustrated structure permits rotation of the waveguide 6 with the paraboloid 5, thereby rotating the orientation of the polarization. Alternatively, if sufficient clearance is provided near the vertex of the paraboloid to allow rotation of waveguide 6 on the paraboloid axis, the waveguide may be rotated without rotating the reflector surface. In either event, aperture I0 will remain substan-. tially fixed with respect to the focal point of the paraboloid unless it is deliberately displaced a small distance, in which case it will rotate around the axis of the paraboloid. Of course, a rotating joint (not shown) which might include a transition section to circular waveguide may be provided, or the entire waveguide could be circular. It has been found that the portion of the waveguide 6 lying in the path of the energy radiating from aperture in and from the paraboloid presents only negligible reflection and interference.

In the preferred embodiment illustrated the waveguide is rectangular, having broad sides H and narrow sides l2 and I3, and it is contemplated to excit the waveguide in the TEo,1 mode so that the electric vector will be perpendicular to the broad sides. The waveguide extending through the paraboloid surface may then be bent so that each broad side remains substantially in its own plane, as shown in the drawing, and thus the electric vectors of energy radiated from aperture I 0 and outwardly from paraboloid are generally perpendicular to the main conducting surface presented to the energy, thus minimizing the interference from parts of the waveguide extending in the path of the energy.

As is well-known in the art, antennas having directive effects in radiation conversely have like directive effects on reception, and similar struc- 2 tures may be used for radiation or reception of electromagnetic energy.

Many variations will be apparent to those skilled in the art, and therefore it is not desired to restrict the scope of the invention to the precise embodiment herein disclosed.

What is claimed is:

1. An antenna comprising a paraboloid reflector and a device for illuminating said reflector, said device comprising a rectangular waveguide having planar broad sides and curved narrow sides and an aperture, said waveguide having a straight portion extending through the vertex of said paraboloid reflector along the axis thereof and havin a hook-like portion continuous therewith so that said aperture terminates substantially at the focal point of said paraboloid and is directed toward said reflector.

2. An antenna comprising a paraboloid reflector and a device for illuminating said reflector, said device comprising a hook shaped waveguide terminating in an aperture, said waveguide extending through the vertex of said paraboloid and being 50 disposed that its aperture terminates substantially at the focal point of said paraboloid and is directed toward the vertex of said reflector.

3. An antenna for effecting translation of energy between electromagnetic waves and a utilization circuit, said antenna comprising a parabolic reflector and means to couple said reflector to said utilization circuit, said means comprising a waveguide having a straight portion and a hook-like portion continuous therewith, said straight portion being positioned through the vertex of said reflector and along the axis thereof, said hook-like portion having a terminal portion co-axial with said straight portion and directed toward said reflector, said terminal portion terminating in a dielectric connection to free space at the focus of said reflector for energy interchange with said reflector.

4. The device according to claim 3, wherein said waveguide comprises two broad parallel sides and two narrow parallel sides, and wherein corresponding sides of said straight portion and "said hook-like portion lie in the same plane.

WILLIAM SICHAK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,206,923 Southworth July 9, 1940 2,422,184 Cutler June 17, 1947 2,427,005 King Sept. 9, 1947 2,429,601 Biskeborn et a1. Oct. 28, 1947 2,429,640 Mieher et al Oct. 28, 1947 

